Lithium titanates are materials under development for the electrodes of lithium ion batteries. The crystal form Li4Ti5O12 (spinel) particularly, because of its favorable intercalation properties, is the preferred form for secondary (rechargeable) batteries.
There are several known methods to make lithium titanate and particularly Li4Ti5O12 spinel. For instance, U.S. Pat. No. 5,545,468 teaches a method to prepare lithium titanate by reacting titanium dioxide in the anatase or rutile form with lithium carbonate or hydroxide in the range 700° to 1000° C.
Recently, it has become apparent that a smaller particle size in the electrode material generally allows a faster charging rate of the lithium ion battery and a larger number of charging cycles without degeneration. Japanese patent application 09-309727 teaches a method to produce lithium titanate structures of long particles containing many voids with a longest dimension of 0.1 to 50 μm and a specific surface area of 1-300 m2/g. The particles are made by reacting a titanium and a lithium compound in solution, precipitating with ammonia, drying, and calcining.
Japanese patent application number 2000-302547 teaches a method to make lithium titanates by calcining a mixture of a titanium and a lithium compound following a multi-step heating and cooling program. The proposed process is stated to provide improved phase control and reduced loss of lithium compared to U.S. Pat. No. 5,545,468. It also allegedly provides cheaper processing without the wastewater treatment problems associated with JP 09-309727. It does not address, however, the issue of crystal size or specific surface area.